Surge / Idle |
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Surge / Idle |
lsintampa |
Dec 22 2014, 08:53 AM
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#1
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Senior Member Group: Members Posts: 520 Joined: 28-January 13 From: Tampa, FL Member No.: 15,441 Region Association: South East States |
75 2.0 FI
I'm in Florida - so the weather outside is somewhat warm (50's maybe right now). I'll try to be as detailed as I can. I've had this issue since I started driving the car - about 8 months ago. It underwent a motor rebuild - along with some other mechanical repairs. All hoses are new (air supply, and fuel). ECU and other FI components are original - best I can tell. When I start the car - it starts right up. At idle RPMs go to about 1500 with a very slight surge (maybe 1450 - 1550). If I pull the air supply that goes to the AAR from the air filter and plug it, the idle goes down to what I'd expect - about 900 RPM still with a little surge. This is while the motor is "cold" - so to speak. Within like a minute of starting. As the car warms - just at idle, the RMPs start to come down and the vacuum from the AAR isn't as strong - but still present. However now the surge is crazy - like from almost a stall up to maybe 1200, back down, back up, etc. Pulling the hose from the AAR - does nothing - I can plug it or leave it and the air filter wide open and there is no change. I put the hose back on - again no change. I did not let it get to a full warm state - IE the temp gauge just started to move up. I've heard there are three states (cold, pre-warm, and fully warm) that come into play. Various tinkering, like turning the air mixture valve to a total closed state, and mucking with the ECU dial has had some success, but at BEST, I get like a 1200 RPM idle still with some surging. To the best of my knowledge there are no air leaks - at least not from any hoses. I've some concerns that the air plenum may have some stress cracks around the support studs. But I don't know that would cause the surging? I'd think the idle would just be high - period. YES / NO? I don't know where to begin to figure out why it behaves this way. Thanks, Len |
r_towle |
Jan 16 2015, 03:23 PM
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#2
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Custom Member Group: Members Posts: 24,574 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
if you remove both the advance and retard vacuum lines from the distributor, and put a bolt in each one so there is no leak at the intake, does the problem resolve?
Starting to suspect your distributor here. rich |
lsintampa |
Jan 17 2015, 12:06 PM
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#3
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Senior Member Group: Members Posts: 520 Joined: 28-January 13 From: Tampa, FL Member No.: 15,441 Region Association: South East States |
if you remove both the advance and retard vacuum lines from the distributor, and put a bolt in each one so there is no leak at the intake, does the problem resolve? Starting to suspect your distributor here. rich Negative. Actually it made it worse - that is if it would start and run at all. With them off, if it does manage to start and stay it surges and will die out. With the hoses on - it starts, idle is maybe 300, or less - and eventually dies out. The idle is so low, it's hard to determine if it is surging at all. Started to wonder if the timing mark is correct? After the motor rebuild it came back with a bright yellow paint line on what I'm assuming is the correct timing mark. Well I double checked the timing marks, and TDC is painted white, and the big yellow blade is @ 27 degrees... so timing appears to be set correctly. I just wanted to double check that TDC was not yellow. The white on the TDC mark was on the back side of the fan, so you can't see it without a mirror. |
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